1. Field of the Invention
The field of the present invention is in the field of semiconductor integrated circuit packaging and, more particularly, deals with packaging of multiple integrated circuits and the control of package temperatures.
2. Prior Art
Heat pipes are well-known in thermomechanical applications, typically involving large industrial apparatus and engines. The conventional, thermomechanical heat pipe consists of a closed container, typically a steel pipe, which has disposed within the interior of the pipe a fibrous or wick material which is saturated by a fluid, typically water, alcohol or some other fluid havng the appropriate vaporization point and latent heats. Heat applied to one portion of the pipe causes the fluid in the adjacent wick material to be vaporized and escape to an interior cavity within the pipe which is devoid of wick material. The liquid lost from the wick material at the point of application of heat is replaced by fluid from adjoining portions of wick material through capillary action. The heated and vaporized fluid travels by convection to a cooler portion of the heat pipe where it condenses and is reabsorbed into adjacent wick material. In this manner, heat is removed from one location and deposited in a cooler location by means of the thermal circuit.
More recently, the thermomechanical heat pipe has been applied to thermal applications in electronic packaging, A. Basiulis and K. S. Sekhon (Hughes Aircraft), "Heat Pipes in Electronic Packaging", Electronic Packaging and Production (Nov. 1978). However, prior art applications of heat pipes to electronic packaging have either been afterthoughts at the device level or have involved large components, each of which supports numerous small heat dissipators or a very few large dissipators. The bulk of prior art devices involves large heat pipes in plate or rod form utilized as thermal sinks for discrete dissipators.
Prior art devices do not include methods of integrating electronic device fabrication and device packaging in such a way that the materials and fabrication technologies associated with device fabrication are either simultaneously, or in parallel, employed to fabricate packages with heat pipe capability. Present art treats device fabrication and device packaging as separate operations utilizing entirely different materials and processes. Packaging generally employs materials such as metals, polymers, ceramics and glases while device fabrication employs mainly semiconductors such as silicon and germanium with their associated dopants, metallizations and passivations. However, new device technologies such as magnetic bubble memories increasingly involve not just conventional materials such as those mentioned but others such as garnet which, for the sake of brevity, will be treated herein under the loose descriptive grouping of semiconductor or semiconductive materials even though they don't meet the technical definition of the term in a formal sense. In order to achieve increasingly necessary improvements in device packaging density in terms of functions and power per unit (volume), problems of thermal dissipation, device intercommunication and interfacing must be overcome. It is the purpose of this application to outline solutions to these problems.
What is needed is some means of utilizing the desirable and beneficial performance capabilities of heat pipes in the field of semiconductor device packaging in an integral manner such that the materials and fabrication technology utilized in circuit manufacturing are either simultaneously, or in parallel, used to manufacture the required packaging as well. This integration will allow heat pipe theoretical performance limits to be achieved in packaging and simultaneously make possible the solution of otherwise untenable interconnection and interfacing problems.